By BitBrainers Editorial
Eli Ben-Sasson, co-inventor of Zcash and CEO of StarkWare, argued publicly earlier this month that the 21 million cap does not make sense and proposed 4% annual inflation instead. The reaction across Bitcoin communities was swift and largely dismissive.
Most of that reaction answered the wrong question. The 21 million cap is not under threat. What is under threat, eventually, is something the debate barely touched.
Two Arguments, One Got Ignored
Ben-Sasson made two separate points. The first was about lost keys: over time, private keys are lost. In the theoretical limit, all keys eventually disappear. A fixed supply therefore becomes a shrinking usable supply.
Most of the pushback focused here. The counter is clean. Satoshi addressed it directly: lost coins only make everyone else's coins worth slightly more. Think of it as a donation to everyone. Bitcoin divides to 100 million satoshis per coin, giving 21 quadrillion total units in circulation. Usability is not the constraint. Lost coins are a feature of a deflationary system, not a flaw.
His second point was flagged almost as an aside: "I'm not even talking about the security problem, looming large on the horizon." He was pointing at miner incentives after Bitcoin's block subsidy ends. The debate moved past it. That was the mistake.
On the Messenger
The credibility context matters before getting to the substance.
Zcash launched with a hard cap of 21 million coins, copied directly from Bitcoin. Ben-Sasson helped design that. His current project, Starknet, raised $287 million from venture capital. Its token is down roughly 99% from its 2024 all-time high.
This is directly relevant because his core argument is that inflation is necessary to keep an asset usable. The token he controls the monetary policy of is nearly worthless. That is evidence about his judgment on that specific claim, not a cheap shot.
Corporate Bitcoin holders have reached very different conclusions about what makes the asset worth holding long term. We covered what long-term institutional conviction actually looks like in practice here.
The debates that matter rarely trend.
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SubscribeThe Security Budget Problem Is Real
Today, roughly 95.5% of the 21 million supply has already been mined, around 20.05 million BTC. The current block subsidy is 3.125 BTC per block. The next halving arrives around April 2028, cutting that to 1.5625 BTC.
By 2140, the subsidy reaches zero. From that point, miners are paid exclusively through transaction fees. Bitcoin's design assumes a mature fee market will sustain enough hash rate to keep the network secure.
That assumption has not been tested. It will not be tested for over a century. Researchers and Bitcoin developers have been modeling the risks around fee variance and miner incentive stability in a pure fee regime for years. The honest answer is that nobody knows with certainty whether it holds.
This is the question worth having. Not whether the 21M cap should change. Whether transaction fees alone can sustain meaningful network security after the last halving cycle ends.
Why 4% Is Still the Wrong Answer
Accepting the security budget concern does not mean accepting Ben-Sasson's solution. Four percent annual inflation would destroy the hard money value proposition Bitcoin was built on.
For comparison, Monero runs a permanent tail emission producing roughly 0.85% annual inflation, trending toward zero over time. That is already considered aggressive by Bitcoin standards. Four percent compounds to something closer to mediocre fiat over long horizons.
Even among researchers who take the security budget question seriously, the ceiling for any theoretical tail emission sits well under 1%. Four percent is not a monetary policy. It is a number that sounds reasonable to people who have not thought hard about compounding.
And it would require a hard fork with near-unanimous consensus that does not exist and is not forming.
What to Actually Watch
Fee market trends across the next two halvings. Post-2024 data is the first real signal on whether block space demand is maturing structurally. Ordinals and Runes showed what high-fee blocks look like during demand spikes. Whether that becomes the baseline or reverts to thin fees is the open question.
Hash rate concentration. If the number of active mining pools continues shrinking after each halving, the security budget concern stops being theoretical and becomes measurable.
The CLARITY Act's path through the US Senate. Institutional adoption at scale means more high-value settlement on the base layer, which feeds directly into miner fee revenue. That bill is one of the cleaner links between regulatory progress and Bitcoin's long-term security economics.
The 21 million cap is not going anywhere. The question of what secures the network after the last block reward is mined is still open, and the time to think clearly about it is now.
Sources
X / EliBenSasson — Eli Ben-Sasson on Bitcoin's supply cap, July 7 2026
Tracxn — StarkWare fundraising data
CoinGecko — STARK token price history
Disclosure: This post is for informational purposes only and does not constitute financial advice. BitBrainers may hold positions in assets mentioned.
